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Galileo Thermometer

Updated on September 24, 2014

The Galileo Thermometer

A Galileo Thermometer stands in the corner by the TV. This Galileo Thermometer was a gift to my father but I don't recall whether I bought it, or my sister did. It's the sort of quirky thing she would have bought, but I have a vague memory of buying it myself thinking he would love it (and he did too). Anyway, that is beside the point, the Galileo Thermometer is a fashionable and interesting household accessory as well as a quirky executive toy and it comes in many varieties these days. I hope this page will introduce you to the Galileo Thermometer and tell you a little of how it works if you have never seen one.

Photo of Galileo Thermometer by Lisa Marie Gabriel

Galileo Thermometer - Simple Tube Versions - The purest form of Galileo Thermometer!

I will always have a soft spot for these simple and colorful Galileo Thermometers because they are like ours! Once you know how to read them, they are surprisingly accurate too!

Dad's Galileo Thermometer
Dad's Galileo Thermometer

Interesting Facts About the Galileo Thermometer

First of all, Galileo did not in fact invent the Galileo Thermometer, he invented the thermoscope, which is an air thermometer.The Galileo thermometer itself was invented around the year 1603 by Galileo's pupil Torricelli.

The Galileo thermometer uses buoyancy in liquids to measure temperature. It consits of a tube full of liquid, usually an inert hydrocarbon, in which glass bulbs are suspended. These bulbs are often made of colored glass so they will look aesthetically pleasing. Because the bulbs are less than half the diameter of the tube, they are able to pass each other freely.

How to read the Galileo Thermometer

The densities of the liquid in the tube will change with temperature and the little glass bulbs all differ in density by a very small amount. As the bulbs are sealed, the liquid inside them does not affect the operation of the thermometre. The glass bulbs rise and fall until their density is equal to the surrounding liquid, or other bulbs stop them.

The least dense bulb is at the top, the most dense at the bottom, and this forms a temperature scale. Of course, the bulbs all have a temperature Tag which is used to adjust density more accurately as well as give a reading. The temperature is shown by the buoyancy of the bulbs which form clusters in the tube.

If a cluster of bulbs forms at the top and another at the bottom, the temperature will be the average of the two closest bulbs floating each side of the gap but if a bulb floats in the gap, the temperature is nearest to the tag on that bulb.

Learn more about Galileo and his Life

The Essential Galileo is a collection of Galileo's writings spanning his entire career.

Dialogue Concerning the Two Chief World Systems: Ptolemaic and Copernican

"Galileo's Dialogue Concerning the Two Chief World Systems, published in Florence in 1632, was the most proximate cause of his being brought to trial before the Inquisition." - Amazon review


Galileo for Kids: His Life and Ideas, 25 Activities (For Kids series)

This great activity book has ideas for interesting experiments for kids and explains Galileo's theories and their importance along with his ideas about art and music.

Galileo, Science and the Church (Ann Arbor Paperbacks)

Galileo's ideas put him in confrontation with the Church in his day, this penetrating account explains how.

Galileo Galilei - When the World Stood Still

An extremely well written biography of Galileo.

How the Galileo Thermometer Works - An an amazing light and music show!

For the first three minutes or so, the Galileo thermometer has its own little lazer and music show, but afterwards you can hear a nice explanation of how it works!

Galileo Thermometre with Glass Globe Barometer - Barometer and Galileo Thermometer combination

Remember when you walked into a big old house and you were greeted by the antique thermometer and perhaps an old grandfather clock? I do! These wooden finish weather stations have just that retro vibe with the addition of a Galileo thermometer too. These would create a great discussion point in the hall when your guests arrive! (And of course, you will be able to explain how they work too!)

Who was Galileo? - Galileo Cards and Images


I do not feel obliged to believe that the same God who has endowed us with sense, reason and intellect has intended us to forgo their use. - Galileo Galilei

Ambient Weather AW-YG737S-RD Admiral Fitzroy Storm Glass and Galileo Thermometer
Ambient Weather AW-YG737S-RD Admiral Fitzroy Storm Glass and Galileo Thermometer

Attractive retro weather station for your hall including an Admiral Fitzroy storm glass which will make a great talking point for guests.


All Truths Card


Was Galileo the greatest scientist of his day? Do you have a Galileo thermometer? Thank you for visiting!

© 2012 Lisa Marie Gabriel

Comments and Reviews on the Galileo Thermometer - Please leave your views here...

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    • srsddn lm profile image

      srsddn lm 5 years ago

      Thanks for the display of Galileo Thermometer. Galileo was really the greatest scientists of the day.

    • Joan Haines profile image

      Joan Haines 5 years ago

      I have been fascinated with these things for a long time. I think they're quite elegant.

    • profile image

      anonymous 5 years ago

      I got one of these from my dad a few years back. I love it.